Overview

Brief Summary

Biology

Brown teal are a nocturnal dabbling duck that hides in grass and overhanging vegetation during the day, and forages in fields for worms and insects, or in estuaries for small shellfish at night. It will also sieve through muddy pools and even search through cow dung for invertebrates (4). In the non-breeding season, the brown teal is social, forming small groups at roost sites. However, during the breeding season, from July to November, pair bonds are formed or re-established and both partners behave very aggressively to defend their territory, occasionally killing invading teals. A nest is built in thick vegetation close to water, in which the female lays five or six eggs, incubating them for 27 – 30 days. The ducklings fledge at 55 days, but will remain with their family until the following breeding season. Adults moult shortly after the ducklings have hatched, migrating to a flock site when the moult is complete (4).

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Description

In breeding plumage, the male ducks have a chestnut-coloured breast, a green head and a white stripe down both sides of the body. Some also have a white neckband. However, in non-breeding plumage, males look identical to females and juveniles, with non-descript mottled brown feathers, although males are slightly larger (4). Males utter soft, high-pitched whistles and pops, whereas females emit low quacks and growls (2).

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Distribution

Range Description

Anas chlorotis is endemic to New Zealand, where it was once widespread in the North, South, Stewart and Chatham Islands, but its range is now much reduced. The current strongholds are on Great Barrier Island, where there were 1,300-1,500 birds in the early 1990s, declining to little over 500 in the early 2000s and increasing to over 600 in 2004, and at Mimiwhangata and Teal Bay on the east coast of Northland where the population declined by 65% in the period between 1988 and 1999 to c.100 individuals in 2001 before increasing to nearly c.350 by 2007 (Williams and Dumbell 1996, M. Williams in litt. 1999,Parrish and Williams 2001, Roxburgh 2005, S. Moore and P. Battley in litt. 2012). The re-introduced population in the northern Coromandel numbered c.500 individuals in early 2008, and is increasing. Its estimated Area of Occupancy is only c.300-500 km2(Callaghan et al. in prep). After a study on Great Barrier Island indicated that the population was halving every 4.1 years and could rapidly decline to extinction intensive management was initiated which has seen populations rising again (Ferreira and Taylor 2003, Roxburgh 2005, Hayes 2006, Sim and Roxburgh 2007). Small islands where birds have previously been introduced and persisted for one to two decades may be too small for long-term survival, and some of these populations appear to be approaching extinction; however, the overall population trend is now positive (M. Williams in litt. 1999, Roxburgh 2005, Sim and Roxburgh 2007). New populations have been established at Tawharanui, Cape Kidnappers and Tuhua Island (A. Booth et al. in litt. 2012); however, for the purposes of this assessment, the number of locations is treated as three, until the long-term outcomes of releases beyond Great Barrier Island, Northland and Coromandel can be judged with confidence.

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Range

Once found throughout the lowland, freshwater wetlands of New Zealand and several offshore islands, the brown teal is now limited to Great Barrier Island, and the east coast of Northland, south of the Bay of Islands. Numbers currently stand at around 1,000 (4). Reintroductions of captive-reared juveniles to Coromandel over four years has resulted in the establishment of a resident breeding population (5). Small populations are also found on Little Barrier Island, Rakitu Island, Kawau Island, Moturoa Island, Tiritiri Matangi Island and Kapiti Island, mainly due to reintroductions (4).

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Ecology

Habitat

Habitat and Ecology

It formerly occurred in a wide range of habitats, including freshwater and coastal wetlands, and inland forests up to 800 m (Worthy 2002). It is now restricted to coastal streams, wetlands and dams in predominantly agricultural environments (M. Williams in litt. 1999). It nests in bowls of grass, always under dense, low vegetation, and usually lays six eggs. It feeds on terrestrial, freshwater and marine invertebrates and terrestrial and freshwater vegetation (Williams and Dumbell 1996, Moore et al. 2006). Peak breeding takes place between May and September, but can occur throughout the year (Sim and Roxburgh 2007). Only the female incubates the eggs (Sim and Roxburgh 2007).

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The brown teal previously inhabited a diverse selection of freshwater wetlands and swamp-forest, particularly in the lowlands, but it is now found only in coastal streams, wetlands and dams near to farmland. It nests in grass bowls under thick vegetation (2). Fossil evidence even suggests that the brown teal was once found in forested areas, far from wetlands (4).

This species has a very small range. Until recently its overall range, area of occupancy, area and quality of habitat, number of locations and sub-populations, and number of individuals were undergoing very rapid declines; however, intensive management has halted the decline and populations are now increasing, with several new populations being established. Despite this recent change in fortunes, it remains classified as Endangered until these trends are consolidated.

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Status

The brown teal is classified as Endangered (EN B1ab(i,ii,iii,iv,v) + 2ab(i,ii,iii,iv,v)) on the IUCN Red List 2004 (1) and is listed on Appendix II of the Convention on the Conservation of Migratory Species (3). It is also listed as Nationally Endangered by the New Zealand Government's Department of Conservation and is fully protected by the New Zealand Wildlife Act 1953 (4).

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Trends

Population

Over 1,100 birds were estimated in 2005 at Great Barrier Island and Northland alone (with c.600 at each) (A. Booth et al. in litt. 2012, N. Hayes in litt. 2012), and the population on Coromandel has been estimated at c.700 birds (N. Hayes in litt. 2012), suggesting that the population numbers c.1,900 individuals, treated here as including c.1,300 mature individuals, based on the assumption that they account for around 2/3 of the total population.

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Although the Maori killed brown teal in very large numbers, when European settlers arrived in New Zealand in 1840, it was still the most abundant waterfowl species in the country. Europeans also hunted the brown teal excessively, but it was the introduction of stoats, weasels, ferrets, hedgehogs, cats and dogs that caused the first major decline of this species. In 1921 the brown teal was declared a protected species, but shooting continued, and was compounded by extensive drainage of wetlands and deforestation, leaving less than 10% of wetlands and 30% of native forests (4). The brown teal population stands today at just under 1,000 individuals (5).

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Management

Conservation Actions

Conservation Actions UnderwayCITES Appendix I. In 2007, a species recovery plan was produced with the goal of securing in the wild a combined protected population of 2,000 birds at 5-10 managed sites by 2010. Following a major audit of the recovery programme in 2000 the population has begun to increase. Over 200 birds are held in captivity. Although initial mainland releases totalling over 1,000 birds (Williams and Dumbell 1996) failed, releases are now conducted in combination with intensive predator control and breeding populations appear to have become established in several locations (Heather and Robertson 1997, Hayes 2006, O'Connor et al. 2007, Sim and Roxburgh 2007), and that the species's total population is entering a recovery phase (Hayes 2010, A. Booth et al. in litt. 2012). At least 139 individuals have now been released in a predator-controlled area of Fiordland on the South Island with the hope of establishing a population (Anon. 2011). Predator control, including that of Purple Gallinule (Pukeko), on Great Barrier Island has also led to stability in this population (Hayes 2010). Hazing fences on roads have been erected to force ducks to either fly or use culverts when passing between favoured feeding sites, these have met with success and are planned for more areas (Hayes 2006, Sim and Roxburgh 2007). Habitat is being restored in Northland and Coromandel with the co-operation of local landowners, and some wetlands are grazed to create improved conditions for teal (Sim and Roxburgh 2007). Research is on-going, focusing on management techniques and habitat requirements (Williams and Dumbell 1996).

Conservation Actions ProposedContinue to implement the species recovery plan. Continue to maintain a viable breeding population at a minimum of two locations on the North Island mainland. Continue measures to increase the population on Great Barrier Island. Continue predator control measures at key sites. Erect more hazing fences in areas where road mortality is greatest. Continue the captive breeding programme as a source of birds for translocations. Continue to encourage public support and involvement (Williams and Dumbell 1996). Conduct research into seasonal starvation events (A. Booth et al. in litt. 2012). Carry out studies into habitat use by the species. Conduct research into causes of declines.

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Conservation

The New Zealand Department of Conservation has produced a brown teal recovery plan which is now in action. Five full time staff and a large team of volunteers monitor the ducks and control predators (4) (5). They also oversee a captive breeding programme and the resulting reintroductions. This programme has been extremely successful in producing captive-reared birds – for every bird taken from the wild, 21.5 have been bred and released, bringing the total number of reintroduced brown teal to 2000 since 1964 (4). Improvements in release techniques using supplementary feeders post-release, and predator control at the release site has increased initial post-release survival rates to more than 60% (5). The captive breeding network in New Zealand consists of 20 holders, made up of wildlife parks, zoos and private individuals, on a completely voluntary basis with no financial support. These collectively produce approximately 100 brown teal for release into the wild each year. This programme is now in the third year of releasing the birds into a major release site in Port Charles, Coromandel, which has proved very successful with 60 – 70 percent survival rate of released birds, which are now breeding and producing young in the wild themselves (5).

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Wikipedia

Brown teal

The brown teal (Anas chlorotis) is a species of dabbling duck of the genus Anas. The Māori name for it is pāteke. For many years it had been considered to be conspecific with the flightless Auckland and Campbell teals in Anas aucklandica; the name "brown teal" has also been largely applied to that entire taxon. Common in the early years of European colonisation, the "brown duck" (as it had been often referred to as) was heavily harvested as a food source. Its numbers quickly fell, especially in the South Island, & in 1921 they became fully protected. Captive breeding & releasing into predator-controlled areas has seen good localised populations re-introduced around the country in recent years.

Contents

Pateke is the progenitor of the flightless Auckland teal and Campbell teals but all are now recognised as separate species on account of their geographic isolation and their plumage, size and genetic distinctions.[2] The insular A. aucklandica and A. nesiotis are recognised as good species, but are still sometimes referred to as being part of the "brown teal group". The use of the name 'pateke' is now common & is specific for this species in question.

Concerns have been raised about establishing genetically similar populations during re-introduction. The original captive pateke were sourced from Great Barrier Island, where only one haplotype was found in abundance, compared with eleven haplotypes found in the other remaining population at Mimiwhangata. The newly released flocks exclusively contain these birds of captive origin, & diversity is perhaps now not being fully represented in the National population[3]

The former population of Fiordland brown teal, which died out by 2013[4] has been replaced with captive-origin birds. Sequencing showed striking similarity to grey duck and mallard sequences, with which they group. It therefore seems extremely likely that the former Fiordland population of brown teal have at sometime in the past hybridised extensively with these invading species[5]

The brown teal is largely nocturnal in habit by dabbling duck standards. This is an evolutionary response to natural diurnal predators such as the New Zealand falcon, Eyles' harrier, or skuas further south in their range. Brown teal have no defense against introduced cats, dogs, stoats & ferrets, which can kill adults & ducklings, or against rats which eat eggs.

It feeds by dabbling and upending, like its relatives. Its diet consists mainly of aquaticinvertebrates like insects and their larvae, or crustaceans. It appears quite fond of mollusks. Small species such as pipi (Paphies australis) and large wedge shell (Macomona liliana) are eaten whole and crushed in the gizzard. For feeding on larger cockles such as Austrovenus stutchburyi (New Zealand cockle), at least some New Zealand teals have developed a peculiar technique, as of now undocumented in other birds, to force their rather soft bills between the cockle shells and tear out the flesh with a jackhammer-like pumping motion. At night brown teal will forage on land some distance from the streams used as a refuge during the day (Worthy 2002).

Nest of dry grass near water or under shelter of large Carex,[6] heavily lined with down. A clutch of four to eight creamy-brown eggs is laid.[7] Incubation by the female alone, takes 27–30 days. The male stays in his territory as a guard, aggressive to all other waterfowl.[8]

This species is endangered and occurs predominantly on offshore islands but also in predator-proof sanctuaries on the mainland such as Tawharanui Regional Park. Formerly, it was widespread on the New Zealand mainland, but it disappeared there due to introduced predators like cats, dogs and rats, which easily preyed on this unwary, weakly flying bird. According to the IUCN categorization as VU D1, fewer than 1000 adult birds remain. The species has recently been upgraded to endangered by Birdlife International (Birdlife 2007), and the change will be reflected in the next update of the IUCN red list.